Contributions of the sympathetic nervous system, glutathione, body mass and gender to blood pressure increase with normal aging: influence of heredity.

Body mass and sympathetic activity increase with aging and might underlie blood pressure (BP) elevation. Increased body mass index (BMI) may elevate BP by increasing sympathetic activity. Glutathione (GSH) can decrease BP, and declines with aging. We measured systolic (SBP) and diastolic BP, BMI, plasma (NE(pl)) and urine norepinephrine (NEu), and plasma GSH in n=204 twins across the age spectrum. BP correlated directly with BMI, NEpl, and NEu, but inversely with GSH. Age correlated with BP, BMI, NEpl, and NEu. BP, BMI, NEpl, and NEu were higher in older subjects than younger subjects, whereas GSH was lower with aging. In older subjects with high (above median) NEpl, SBP was 8 mmHg higher than in those of comparable age with low NE. In younger subjects with high GSH, BP was significantly lower than in younger subjects having low GSH. NEu was significantly reduced in young high-BMI subjects vs young low-BMI subjects. The heritability (h2) of NEpl, NEu, and GSH ranged from approximately 50 to approximately 70%, and these biochemical quantities were considerably more heritable than BP. We conclude that increases in sympathetic activity contribute to aging-induced SBP elevations, especially in older females. GSH reductions apparently participate in aging-induced BP elevations, most strongly in males. BMI increases contribute to BP elevations, particularly in younger subjects. BMI elevations apparently raise BP mainly by peripheral mechanisms, with generally little sympathetic activation. Substantial h(2) for plasma GSH, NE, and urine NE suggests that such traits may be useful 'intermediate phenotypes' in the search for genetic determinants of BP.

Elevated S-adenosylhomocysteine in Alzheimer brain: influence on methyltransferases and cognitive function.

Hyperhomocysteinemia is common in Alzheimer's disease and is negatively correlated with cognitive function. Hyperhomocysteinemia can increase S-adenosylhomocysteine (SAH), a potent methyltransferase inhibitor. This study investigates the role of brain SAH in the cognitive and neurological disruption in Alzheimer's disease. SAH was significantly (26%) higher in prefrontal cortex of Alzheimer patients than normals. Brain homogenates from Alzheimer patients inhibited an exogenous methyltransferase 15% more than normal homogenates (P <.001). Brain SAH levels correlated (r=.508) with methyltransferase inhibition by brain homogenates. Methyltransferase inhibition by Alzheimer brain homogenates correlated inversely with cognitive function as determined by MMSE (r=-0.36). Phenylethanolamine N-methyltransferase (PNMT) and catechol O-methyltransferase (COMT) activities were more than 30% lower (P<0.001) in Alzheimer than normal brains. Brain PNMT activity correlated significantly with cognitive function (r=0.243), age of Alzheimer's onset (r=0.272), and choline acetyltransferase activity (r=0.333), but negatively with neurofibrillary tangles (r=-0.332). COMT activity also correlated significantly with cognitive function (r=0.324), age of disease onset (r=0.209), choline acetyltransferase activity (r=0.326), levels of synaptophysin (r=0.506), and negatively with tangles (r=-0.216 P=0.039). Elevated SAH in Alzheimer brain inhibits methyltransferases and is related to markers of disease progression and cognitive impairment.

Development of a robust scintillation proximity assay for protein tyrosine phosphatase 1B using the catalytically inactive (C215S) mutant.

Protein tyrosine phosphatases are a class of enzymes that function to modulate tyrosine phosphorylation of cellular proteins and play an essential role in regulating cell function. PTP1B has been implicated in the negative regulation of the insulin signaling pathway by dephosphorylating the activated insulin receptor. Inhibiting this phosphatase and preventing the insulin-receptor downregulation has been suggested as a target for the treatment of Type II diabetes. A high-throughput screen for inhibitors of PTP1B was developed using a scintillation proximity assay (SPA) with GST-- or FLAG--PTP1B((1-320)) and a potent [(3)H]-tripeptide inhibitor. The problem of interference from extraneous oxidizing and alkylating agents which react with the cysteine active-site nucleophile was overcome by the use of the catalytically inactive C215S form of the native enzyme (GST--PTP1B(C215S)). The GST--PTP1B was linked to the protein A scintillation bead via GST antibody. The radiolabeled inhibitor when bound to the enzyme gave a radioactive signal that was competed away by the unknown competitive compounds. Further utility of PTP1B(C215S) was demonstrated by mixing in the same well both the catalytically inactive GST--PTP1B(C215S) and the catalytically active FLAG--CD45 with an inhibitor. Both a binding and kinetic assay was then performed in the same 96-well plate with the inhibition results determined for the PTP1B(C215S) (binding assay) and CD45 (activity assay). In this way inhibitors could be differentiated between the two phosphatases under identical assay conditions in one 96-well assay plate. The use of a mutant to reduce interference in a binding assay and compare with activity assays is also amenable for most cysteine active-site proteases.

Does the state you live in make a difference? Multilevel analysis of self-rated health in the US.

This paper investigates the different sources of variation between US states in self-rated health using multilevel statistical procedures. The different sources that are considered are based on individual- and state-level factors. Data for the analysis comes from the 1993-94 Behavioral Risk Factor Surveillance System and the 1986-90 General Social Surveys. Results show that individual-level factors (such as low income, being black, smoking) are strongly associated with self-rated poor health. Significant variation, however, remain between states after allowing for individual characteristics. Crucially, between-state variation in self-rated health is different for different income groups. State-level contextual effects are found for per-capita median-income and 'social capital'. While not strong, there seems to be a differential impact of state income-inequality on high-income groups, such that the affluent report better health from living in high inequality states. The paper substantiates the need to connect individual health to their macro socioeconomic context. Importantly, it is argued that without adopting an explicitly multilevel approach, the debate on linkages between individual health and income-inequality/social capital cannot be adequately addressed.

Genomic characterization of the human and mouse protein tyrosine phosphatase-1B genes.

PTP-1B is a ubiquitously expressed intracellular protein tyrosine phosphatase (PTP) that has been implicated in the negative regulation of insulin signaling. Mice deficient in PTP-1B were found to have an enhanced insulin sensitivity and a resistance to diet-induced obesity. Interestingly, the human PTP-1B gene maps to chromosome 20q13.1 in a region that has been associated with diabetes and obesity. Although there has been a partial characterization of the 3' end of the human PTP-1B gene, the complete gene organization has not been described. In order to further characterize the PTP-1B gene, we have cloned and determined the genomic organization for both the human and mouse PTP-1B genes including the promoter. The human gene spans >74 kb and features a large first intron of >54 kb; the mouse gene likewise contains a large first intron, although the exact size has not been determined. The organization of the human and mouse PTP-1B genes is identical except for an additional exon at the 3' end of the human that is absent in the mouse. The mouse PTP-1B gene maps to the distal arm of mouse chromosome 2 in the region H2-H3. This region is associated with a mouse obesity quantitative trait locus (QTL) and is syntenic with human chromosome 20. The promoter region of both the human and mouse genes contain no TATA box but multiple GC-rich sequences that contain a number of consensus SP-1 binding sites. The basal activity of the human PTP-1B promoter was characterized in Hep G2 cells using up to 8 kb of 5' flanking sequence. A 432 bp promoter construct immediately upstream of the ATG was able to confer maximal promoter activity. Within this sequence, there are at least three GC-rich sequences and one CCAAT box, and deletion of any of these elements results in decreased promoter activity. In addition, the promoter in a number of mouse strains contains, 3.5 kb upstream of the start codon, an insertion of an intracisternal a particle (IAP) element that possibly could alter the expression of PTP-1B mRNA in these strains.

Social capital and self-rated health: a contextual analysis.

OBJECTIVES: Social capital consists of features of social organization--such as trust between citizens, norms of reciprocity, and group membership--that facilitate collective action. This article reports a contextual analysis of social capital and individual self-rated health, with adjustment for individual household income, health behaviors, and other covariates. METHODS: Self-rated health ("Is your overall health excellent, very good, good, fair, or poor?") was assessed among 167,259 individuals residing in 39 US states, sampled by the Behavioral Risk Factor Surveillance System. Social capital indicators, aggregated to the state level, were obtained from the General Social Surveys. RESULTS: Individual-level factors (e.g., low income, low education, smoking) were strongly associated with self-rated poor health. However, even after adjustment for these proximal variables, a contextual effect of low social capital on risk of self-rated poor health was found. For example, the odds ratio for fair or poor health associated with living in areas with the lowest levels of social trust was 1.41 (95% confidence interval = 1.33, 1.50) compared with living in high-trust states. CONCLUSIONS: These results extend previous findings on the health advantages stemming from social capital.

Enhancement of leukocyte response to lipopolysaccharide by secretory group IIA phospholipase A2.

Secretory nonpancreatic group IIA phospholipase A2 (sPLA2), a lipolytic enzyme found in plasma, is thought to play an important role in inflammation. In patients with sepsis, a strong positive correlation is observed between the plasma level of sPLA2 and poor clinical outcome in sepsis. We have thus asked whether sPLA2 could play a role in enabling responses of cells to bacterial lipopolysaccharide (LPS), a key contributor to sepsis. In the presence of sPLA2, cellular responses to LPS were significantly increased. This was demonstrated in assays of LPS-stimulated interleukin-6 (IL-6) production in whole blood and binding of freshly isolated human polymorphonuclear neutrophils (PMN) to fibrinogen-coated surfaces. We further found that sPLA2 enhanced binding of labeled LPS to PMN, and that the sPLA2-mediated cell responses to LPS were all blocked by monoclonal antibodies directed against membrane CD14. Two properties ofsPLA2 may contribute to its activity to mediate responses to LPS. sPLA2 appears to bind LPS because pre-exposure of sPLA2 to LPS led to a dose-dependent increase in its ability to hydrolyze phospholid substrate, and incubation of sPLA2 with BODIPY-LPS micelles resulted in enhanced fluorescence, presumably from the disaggregation of the LPS aggregates. Additional studies demonstrated that the esterolytic function of sPLA2 is also needed both for the disaggregation of LPS and CD14-dependent cell stimulation. The precise mechanisms by which LPS-binding and esterolytic activity contribute to sPLA2 activity are not clear but our data strongly suggest that these activities result in interaction of LPS with CD14 and subsequent cell activation.

Women's status and the health of women and men: a view from the States.

We examined the status of women in the 50 American states in relation to women's and men's levels of health. The status of women in each state was assessed by four composite indices measuring women's political participation, economic autonomy, employment and earnings, and reproductive rights. The study design was cross-sectional and ecologic. Our main outcome measures were total female and male mortality rates, female cause-specific death rates and mean days of activity limitations reported by women during the previous month. Measures of women's status were strikingly correlated with each of these health outcomes at the state level. Higher political participation by women was correlated with lower female mortality rates (r = -0.51), as well as lower activity limitations (-0.47). A smaller wage gap between women and men was associated with lower female mortality rates (-0.30) and lower activity limitations (-0.31) (all correlations, P < 0.05). Indices of women's status were also strongly correlated with male mortality rates, suggesting that women's status may reflect more general underlying structural processes associated with material deprivation and income inequality. However, the indices of women's status persisted in predicting female mortality and morbidity rates after adjusting for income inequality, poverty rates and median household income. Associations were observed for specific causes of death, including stroke, cervical cancer and homicide. We conclude that women experience higher mortality and morbidity in states where they have lower levels of political participation and economic autonomy. Living in such states has detrimental consequences for the health of men as well. Gender inequality and truncated opportunities for women may be one of the pathways by which the maldistribution of income adversely affects the health of women.

Cytogenetic and radiation hybrid mapping of human arachidonate 5-lipoxygenase-activating protein (ALOX5AP) to chromosome 13q12.

Arachidonate 5-lipoxygenase-activating protein (ALOX5AP) is an arachidonic acid binding protein that has been shown to be critical in the biosynthesis of leukotrienes. We mapped the ALOX5AP gene to the chromosome 13q12 region by cytogenetic mapping, yeast artificial chromosome (YAC) pool screening, and radiation hybrid mapping. It was mapped to YAC contig WC13.2 by YAC pool screening with an unambiguous hit to WI-4874, which is at 78 cR on the radiation hybrid map, 3.36 cR, by radiation hybrid mapping, from WI-4874.

Regulation of the cellular expression of secretory and cytosolic phospholipases A2, and cyclooxygenase-2 by peptide growth factors.

Secretory group II (sPLA2) and cytosolic (cPLA2) phospholipases A2 and cyclooxygenase-2 (Cox-2) play a pivotal role in release of proinflammatory eicosanoids. Excessive activity of sPLA2 per se can also propagate inflammation. Endogenous control of the above enzymes has not been completely elucidated. We investigated the combined impact of promoting cytokines and inhibitory peptide growth factors on the expression of mRNA of the above enzymes, on protein content and extracellular release of sPLA2 and on PGE2 production in osteoblasts (FRCO). The synthesis and release of sPLA2 were enhanced by about 20-fold by 0.5 ng/ml IL-1beta or by 50 ng/ml of TNFalpha. Coaddition of both cytokines resulted in synergistic 150-fold increase in the release of sPLA2 implying the existence of two paths of induction. IL-1beta and TNFalpha markedly enhanced the transcription of sPLA2 mRNA. Kinetic study showed that IL-1/TNF initiated sPLA2 release after 12 h, reaching maximum at 48 h. IL-1alpha was a weak stimulator of sPLA2 release, whereas IL-6, IL-8, IGF, IFN-gamma, growth hormone, insulin and GM-CSF were not stimulatory. Peptide growth hormones TGFbeta, PDGF-BB, EGF and bFGF markedly inhibited the extracellular release of sPLA2. TGFbeta and PDGF-BB significantly reduced the level of sPLA2 mRNA, thus acting upon transcription whereas EGF and bFGF were not inhibitory, acting rather upon the translational or posttranslational steps. IL-1/TNF and growth factors had no significant effect on cPLA2 mRNA expression. Cox-2 mRNA expression was markedly enhanced by IL-1/TNF and suppressed by all growth factors tested. Cytokines enhanced the extracellular release of PGE2 and further enhancement was induced by growth factors with the exception of TGFbeta. Cycloheximide abolished completely the release of sPLA2 and markedly reduced the release of PGE2 from cytokine-stimulated FRCO, regardless of whether growth factors were present or not. NS-398, a specific inhibitor of Cox-2 abolished almost completely the release of PGE2 from cytokine-stimulated cells, regardless of the presence of growth factors. Thus, different signalling mechanisms are involved in the impact of growth factors on mRNA expression of sPLA2, cPLA2 and Cox-2. The differences between the impact on FRCO sPLA2 and that reported in other cells, imply that endogenous control of arachidonic acid cascade is cell-specific.

Overexpression of the nonpancreatic secretory group II PLA2 messenger RNA and protein in colorectal adenomas from familial adenomatous polyposis patients.

The synovial fluid or group II secretory phospholipase A2 (sPLA2) has been implicated in various inflammatory processes and has been shown to release arachidonic acid for prostaglandin biosynthesis. In human colorectal cancer, both arachidonic acid and eicosanoid levels are elevated. Recently, sPLA2 has been identified as a candidate gene that modifies the Apc gene in the Min mouse, a murine model for familial adenomatous polyposis (FAP). Loss of sPLA2 gene function results in susceptibility to the Min phenotype and the formation of multiple intestinal polyps, whereas mice expressing an active sPLA2 gene are resistant to polyp formation. Therefore, there are two potentially contrasting roles for sPLA2 in colon cancer; one is protection against polyp formation, and the other, the release of arachidonic acid for prostaglandin production and subsequent tumor promotion. To investigate these contrasting dual roles of sPLA2, we have examined the expression and sequence of the sPLA2 mRNA in normal mucosa and duodenal and colorectal polyps from FAP patients. In 11 of 14 patients, there was a significant increase in sPLA2 mRNA levels in the adenoma over the normal tissue. In some cases, there was over 100-fold increase in mRNA levels in the adenoma compared with normal tissue. Analysis of multiple adenomatous polyps from individual patients revealed that not all polyps contained elevated levels of sPLA2 mRNA. Immunoblot analysis also showed that sPLA2 protein expression was elevated in adenoma over normal tissue in five of six FAP patients analyzed. Furthermore, sequence analysis of sPLA2 mRNA present in these samples did not reveal mutations in the coding region. The implications of the up-regulation of sPLA2 in FAP is not clear, but unlike the Min mouse model, it does not seem to have a significant effect on polyp formation. In contrast, the high level of sPLA2 expression is more likely contributing to the elevated levels of arachidonic acid found in colorectal cancer and, in conjunction with the elevated expression of cyclooxygenase-2, could be another factor in tumor formation.

Social capital, income inequality, and mortality.

OBJECTIVES: Recent studies have demonstrated that income inequality is related to mortality rates. It was hypothesized, in this study, that income inequality is related to reduction in social cohesion and that disinvestment in social capital is in turn associated with increased mortality. METHODS: In this cross-sectional ecologic study based on data from 39 states, social capital was measured by weighted responses to two items from the General Social Survey: per capita density of membership in voluntary groups in each state and level of social trust, as gauged by the proportion of residents in each state who believed that people could be trusted. Age-standardized total and cause-specific mortality rates in 1990 were obtained for each state. RESULTS: Income inequality was strongly correlated with both per capita group membership (r = -.46) and lack of social trust (r = .76). In turn, both social trust and group membership were associated with total mortality, as well as rates of death from coronary heart disease, malignant neoplasms, and infant mortality. CONCLUSIONS: These data support the notion that income inequality leads to increased mortality via disinvestment in social capital.

Microtubule depolymerization selectively down-regulates the synthesis of proinflammatory secretory nonpancreatic phospholipase A2.

Microtubule depolymerizing agents (MTD) diminish the expression of cell surface receptors for TNF-alpha. Because TNF-alpha along with IL-1 beta markedly enhance the gene expression and extracellular release of proinflammatory secretory nonpancreatic phospholipase A2 (sPLA2), we tested the impact of MTD on the expression of sPLA2. We report that MTD markedly inhibit the expression and release of sPLA2 by fetal rat calvarial osteoblasts (FRCO), which synthesize and release sPLA2. When FRCO were pretreated with colchicine and then stimulated with IL-1 beta 0.2 ng/ml and TNF-alpha 25 ng/ml (IL-1/TNF), minute quantities of colchicine (1.25 nM) reduced the released sPLA2 activity to 11% of that in controls. IC50 was 0.75 nM. When IL-1/TNF and colchicine were added simultaneously, similar inhibition (8% of that in controls) required higher concentrations of colchicine (0.125 microM). IC50 was 68.75 nM. When FRCO were prestimulated by IL-1/TNF, much higher concentrations of colchicine were required to reduce sPLA2 activity. MTD inhibited the expression of sPLA2 by a mechanism(s) different from the way in which they impact TNF surface receptors, because they inhibited sPLA2 expression in FRCO stimulated by IL-1 beta or by cell-permeable cAMP analogs. Colchicine (1 microM) reduced the expression of sPLA2 induced by dibutyryl cAMP (2 mM) and 8-bromo-cAMP (4 mM) to 38% and 58% of that n controls, respectively. Photoinactivated lumicolchicines beta and gamma were noninhibitory. Microtubular stabilizer taxol (5 microM) abolished inhibitory activity of colchicine, increasing the expression of sPLA2 3.2-fold compared with that in control cells cultured without taxol. Other MTD, such as vinblastine (0.01 microM), inhibited sPLA2 release to 27% of the controls, whereas nocodazole (10 microM) was less inhibitory. Northern blot analysis of FRCO showed that sPLA2 mRNA was greatly induced by IL-1/TNF. The induction of sPLA2 mRNA by IL-1/TNF was nearly completely abolished by colchicine in a dose-related manner. Western blot analysis of intra- and extracellular sPLA2 protein showed complete inhibition of the synthesis by MTD. To determine whether the inhibition of sPLA2 is selective, mRNA levels of cytosolic PLA2 and of inducible cyclooxygenase-2 were investigated. Colchicine had no effect on the mRNA levels of these two enzymes, which suggests that the inhibitory effect of MTD on sPLA2 expression is selective and occurs at the transcriptional level. Thus, the microtubular system plays a significant role in the synthesis of proinflammatory sPLA2, a fact that may explain in part the anti-inflammatory activity of microtubular disrupters.

Characterization of autocrine inducible prostaglandin H synthase-2 (PGHS-2) in human osteosarcoma cells.

The human osteosarcoma 143.98.2 cell line was found to express high levels of prostaglandin synthase-2 (PGHS-2) without detectable levels of prostaglandin synthase-1 (PGHS-1) as measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblot analysis. Maximal levels of PGHS-2 induction were attained when the cells were grown beyond confluence. The osteosarcoma cells also secrete IL-1 alpha, IL-1 beta and TNF alpha in the culture medium. PGHS-2 expression was inducible by the exogenous addition of these cytokines as well as conditioned media from auto-induced cultures and inhibitable by treatment with dexamethasone. In contrast, undifferentiated U937 cells selectively express PGHS-1 as analyzed by RT-PCR and Western blotting. The effects of non-steroidal anti-inflammatory drugs (NSAIDs) on the cellular PGE2 production mediated by each isoform of human PGHS were determined using osteosarcoma and undifferentiated U937 cells. When cells were preincubated with inhibitors to allow time-dependent inhibition prior to arachidonic acid stimulation, NS-398, CGP 28238, L-745,337, SC-58125 all behaved as potent (IC50 = 1-30 nM) and selective inhibitors of PGHS-2, in contrast to indomethacin, flurbiprofen or diclofenac which are potent inhibitors of enzymes. DuP-697 and sulindac sulfide were also potent inhibitors of PGHS-2 but both compounds inhibited cellular PGHS-1 activity at higher doses (IC50 = 0.2-0.4 microM). Time-dependent inhibition of PGE2 production in osteosarcoma cells was observed for indomethacin, diclofenac and etodolac. The synthesis of PGE2 by U937 cells was strongly dependent on exogenous arachidonic acid (100-fold stimulation) whereas confluent osteosarcoma cells also produced PGE2 without exogenous stimulus (7-fold stimulation by arachidonic acid). Osteosarcoma cells grown beyond confluence released more PGE2 from endogenous substrate than arachidonic acid stimulated undifferentiated U937 cells. These results indicate that osteosarcoma cells selectively express PGHS-2 with an autocrine regulation and effective utilization of endogenous arachidonic acid for PGE2 synthesis.

The effects of the menstrual cycle, race, and gender on adrenergic receptors and agonists.

OBJECTIVE: To examine possible effects of race, sex, and the menstrual cycle on adrenergic receptors (beta 2 and alpha 2) and agonists. METHODS: Sixty-three normotensive black men and women and white men and women were studied twice, approximately 6 weeks apart. Women were studied once during the follicular phase and once during the luteal phase of the menstrual cycle. beta 2-Adrenergic receptors and adenylate cyclase activity were examined on lymphocytes, and alpha 2-adrenergic receptors were examined on platelets. Norepinephrine and epinephrine were determined in plasma. RESULTS: Women showed greater lymphocyte beta 2-receptor sensitivity (isoproterenol-stimulated cyclic adenosine monophosphate; p = 0.009). Women also showed greater postreceptor adenylate cycle activity independent of the beta-receptor (forskolin stimulation; p = 0.006). When these differences were controlled for, the gender-related differences in beta 2-receptor sensitivity were no longer evident. Black women had a reduced beta 2-receptor sensitivity in the luteal phase compared with the follicular phase, whereas white women showed no significant change (p = 0.018). Black subjects had lower lymphocyte beta 2-receptor density (Bmax) values than white subjects (p = 0.047). There were no significant effects on alpha 2-adrenergic receptors. CONCLUSION: The findings suggest that although there is no generalized effect of the menstrual cycle on adrenergic receptors in white women, such an effect may occur in black women. The findings also suggest that previously reported gender-related differences in beta 2-receptor sensitivity may be due to gender-related differences in postreceptor activity and not the beta 2-receptor per se.

Income distribution and mortality: cross sectional ecological study of the Robin Hood index in the United States.

OBJECTIVE: To determine the effect of income inequality as measured by the Robin Hood index and the Gini coefficient on all cause and cause specific mortality in the United States. DESIGN: Cross sectional ecological study. SETTING: Households in the United States. MAIN OUTCOME MEASURES: Disease specific mortality, income, household size, poverty, and smoking rates for each state. RESULTS: The Robin Hood index was positively correlated with total mortality adjusted for age (r = 0.54; P < 0.05). This association remained after adjustment for poverty (P < 0.007), where each percentage increase in the index was associated with' an increase in the total mortality of 21.68 deaths per 100,000. Effects of the index were also found for infant mortality (P = 0.013); coronary heart disease (P = 0.004); malignant neoplasms (P = 0.023); and homicide (P < 0.001). Strong associations were also found between the index and causes of death amenable to medical intervention. The Gini coefficient showed very little correlation with any of the causes of death. CONCLUSION: Variations between states in the inequality of income were associated with increased mortality from several causes. The size of the gap between the wealthy and less well off--as distinct from the absolute standard of living enjoyed by the poor--seems to matter in its own right. The findings suggest that policies that deal with the growing inequities in income distribution may have an important impact on the health of the population.

Functional identification of the active-site nucleophile of the human 85-kDa cytosolic phospholipase A2.

Ser-228 has been shown to be essential for the catalytic activity of the human cytosolic phospholipase A2 (cPLA2). However, its involvement in catalysis has not yet been demonstrated. Using site-directed mutagenesis, active-site directed irreversible inhibitors, and the novel fluorogenic substrate 7-hydroxycoumarinyl gamma-linolenate, evidence is presented to show that the hydroxyl group of Ser-228 is the catalytic nucleophile of cPLA2. Replacement of Ser-228 by Ala, Cys, or Thr resulted in the inability of these mutants to mediate calcium ionophore induced PGE2 production in COS-7 cells cotransfected with the cPLA2 mutants and cyclooxygenase-1. Cell lysates from these transfected cells also had undetectable levels of cPLA2 phospholipid hydrolyase activity as did the affinity column purified S228A and S228C cPLA2 mutants overexpressed in insect cells. The loss in activity was not due to the inability of the mutant enzymes to translocate to the substrate lipid interface since the purified S228C cPLA2 mutant, like the wild type, translocated to the phospholipid membrane in the presence of calcium as judged by fluorescence energy transfer. However, when an activated substrate, 7-hydroxycoumarinyl gamma-linolenate (pKa approximately 7.8 for its leaving group) was used as substrate, there was a significant level of 7-hydroxycoumarin esterase (7-HCEase) activity (about 1% of wild type) associated with the purified S228CC cPLA2 mutant. The S228A cPLA2 mutant was catalytically inactive. Contrary to wild type cPLA2, the 7-HCEase activity of the thio-cPLA2 was not titrated by the irreversible active-site-directed inhibitor methyl arachidonyl fluorophosphonate, but rather titrated by one equivalent of arachidonyl bromomethyl ketone, an arachidonyl binding site directed sulfhydryl reagent. These results are compatible with the hydroxyl of Ser-228 being the catalytic nucleophile of cPLA2 and that cysteine can replace serine as the nucleophile, resulting ina thiol-cPLA2 with significantly reduced catalytic power.

Factitious pheochromocytoma: novel mimickry by Valsalva maneuver and clues to diagnosis.

Factitious pheochromocytoma usually occurs in patients surreptitiously ingesting adrenergic medications. We encountered a case of factitious pheochromocytoma where in the subject mimicked hemodynamic (profound hypertension) and biochemical (plasma catecholamine elevation) manifestations of the illness by consciously altering autonomic function with Valsalva maneuver. Clues to this presentation included visible performance of Valsalva maneuver, marked disparity between blood pressures recorded in the presence and absence of the subject's knowledge, normal urinary catecholamine and metabolite excretion, and normal plasma chromogranin A. We reproduced, in part, the hemodynamic and biochemical manifestations of this presentation with Valsalva maneuver in healthy subjects.